Fourier transform infrared (FTIR) spectrometry, which is accurate, simple and efficient and has high resolution, was used to investigate the physiological changes in chemical composition of Polygonum lapathifolium during the nutrient solutions supplemented with concentration of Mn2+ (0.005,0.2,0.5,1.0,2.0, 5.0,10.0 mmol·L1). Using the roots, stems and leaves of P. Lapathifolium, absorption bands corresponding to carbohydrates, ester and proteins vary differently. The absorption band heights at 3 420 and 2 926 cm'1 of stem tissues rise firstly and then decrease, indicating that the exudation and transporting situation of organic substances serves as organic osmotic contents to enhance manganese tolerance under low treatments. Meanwhile, the band heights at 2 920 cm-1 (roots) and 1 630 cm-1 (leaves) which have different tendencies in accordance with manganese treatments show that the capability to chelate manganese decreases at higher manganese supply level. In addition, the changes of the bands at 1 060 cm-1 differs from each other, suggesting that under the conditions of severe manganese stress the ex-oxidation of membrane lipid increases. All the results imply that it is practical to apply FTIR to explore the physiological mechanism of manganese tolerance by higher plants.%采用准确度好和分辨率高、简便快捷的傅里叶变换红外光谱法(FTIR)研究在不同锰浓度(0.005，0.2，0.5，2.0和10.0 mmo1·L-1时酸模叶蓼根、茎和叶化学组分的变化。研究结果表明：茎组织在3 420 cm-1和2 920 cm-1处峰高先上升后下降，表明糖类和氨基酸等有机物在锰浓度较低时往往作为渗透性调节物质出现，当锰浓度升高时增强其耐锰性，但其合成和运输受限，含量逐渐下降；根和叶组组织分别在2 920 cmi-1和1 630 cm-1处表现为酸模叶蓼分泌有机酸不断螯合锰，造成羧酸O-H减少；随着锰浓度的升高，其羧酸螯合力变弱;叶组织在1 630 cm-1处的显著吸收峰可能与酸模叶蓼叶中氨基酸、多肽和蛋白质类物质含量增大有关；酸模叶蓼根、茎、叶在1 060 cm-1处最高浓度下峰值的变化，主要表现为膜脂过氧化，这可能与酸模叶蓼的锰耐性有关。因此，利用FTIR研究植物化学组分的变化有助于探讨植物的重金属耐性机理。
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